Delete ROADMAP.md

[martins0n]

Before submitting (must do checklist)

• Did you read the contribution guide?
• Did you update the docs? We use Numpy format for all the methods and classes.
• Did you write any new necessary tests?
• Did you update the CHANGELOG?

Proposed Changes

Closing issues

[github-actions]

🚀 Deployed on https://deploy-preview-904--etna-docs.netlify.app

[codecov-commenter]

Codecov Report

Merging #904 (71e2d5a) into master (8a8cefa) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #904   +/-   ##
=======================================
  Coverage   84.90%   84.90%           
=======================================
  Files         133      133           
  Lines        7548     7548           
=======================================
  Hits         6409     6409           
  Misses       1139     1139           

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